This invention pertains to pipe fittings and, more particularly, fittings for coupling a flanged pipe to a threaded pipe.
When assembling pipe for fluid equipment manufacture, plumbing, and other applications, it is often necessary to couple a flanged pipe to a threaded pipe. The conventional method of joining a flanged pipe to a threaded pipe utilizes a nut slidably disposed on the flanged pipe, the nut having a threaded portion that is large enough to fit over the flange and engage the threaded pipe. The nut includes an inwardly extending flange at its back end, whereby the aperture at the back end of the nut is smaller than the pipe flange, so that the flanged pipe is pulled toward, and held tightly to, the threaded pipe as the nut is tightened.
A disadvantage to this conventional method is that the nut cannot be slid over the flange on the pipe. The nut must therefore be slid onto the opposite end of the pipe, and along the length of the pipe to its final position. This requirement can be impractical and/or impossible when the opposite end of the flanged pipe is already connected to another apparatus or pipe, or when the pipe has an enlarged portion, bend, mounting bracket, or other impediment to sliding the nut along the length of the pipe. Another disadvantage of this conventional method is that assembly and disassembly of the joint generally requires that a length of the flanged pipe equal to the axial length of the nut be free from obstruction. This obstruction-free length is required in order to allow sufficient room to back the nut off of the threaded portion of the pipe. In many plumbing applications it is desirable to locate components very close together, and the conventional nut for flanged pipes presents an undesirable design constraint.
There have been attempts in the prior art to remedy these problems. One example of a previously available nut configuration is shown in U.S. Pat. No. 4,516,278 to Lamond. Lamond discloses a plumbing trap with a collar for connecting a flanged pipe to a threaded pipe. Lamond uses a collar nut that has two opposed locking ears that extend inward. The locking ears engage the flange of the flanged pipe by temporarily deforming and snapping over the flange of the flanged pipe. Lamond also discloses a ferrule and a split brass washer that are received in the nut between the ends of the flanged pipe and the threaded pipe for sealing.
U.S. Pat. No. 1,244,100 to Kortas discloses a pipe coupling utilizing a split reducer having a threaded inner aperture for engaging the threaded portion of the pipe, and a threaded outer portion. A threaded casing screws onto the split reducer to hold them together so that the assembled unit essentially replicates the conventional nut described above. Assembly is complicated, however, requiring first utilizing lugs at the ends of the split reducer to screw the reducer into the casing, and then screwing the unit onto the threaded pipe. In addition no mechanism is provided to properly align the threaded reducer halves so that they properly engage the casing.
U.S. Pat. No. 1,201,022 to Conniff similarly discloses a pipe coupling that uses a split nut with a locking ring for holding the split nut together. Conniff, however, teaches using a circumferential groove on the locking ring inner surface that accommodates a pair of narrow lugs on the split nut. This invention is also difficult to use, however, requiring that a first half of the split nut be first inserted through a longitudinal groove in the locking ring to engage the circumferential groove, then the locking ring is rotated 180 degrees and the second half of the split ring nut is inserted through the same longitudinal groove to engage the circumferential groove. The assembled unit is then screwed onto the threaded portion of the pipe in a manner similar to the conventional nut described above.
In U.S. Pat. No. 5,775,743 to Rochelle, the inventor of the present application discloses a two-piece nut assembly including a nut having an inside diameter that slides over a pipe flange, and a one-piece split insert that fits within the nut to retain nut on the flange. While providing an innovative solution to the disadvantages of conventional couplings discussed above, the split ring must be twisted out of shape for installation.
It will be appreciated that all of these prior art designs incorporate a locking ring or nut that must be unscrewed, and therefore assembly and disassembly will require that the nut move laterally along the flanged pipe for a distance at least equal to the length of the nut. Therefore (assuming a typical joint wherein the threaded and flanged pipes are laterally constrained) a portion of the flanged pipe must remain free of obstructions, to permit disassembly of the joint.
What is needed, therefore, is a coupling assembly for joining a threaded pipe to a flanged pipe that is easy to use, can be installed without requiring sliding a coupling nut along the length of the pipe, and minimizes the length of the flanged pipe that must be kept free of obstruction.
A split nut assembly for releasably coupling a pipe having an externally threaded end with a pipe having an annular flange is disclosed. The split nut assembly includes a two-piece split nut having a threaded inner surface adapted to engage the threaded pipe end and an inwardly disposed flange portion adapted to engage the flanged pipe end. At least one protrusion is provided on the outer surface of the two-piece split nut. A locking ring having at least one inwardly disposed channel slidably engages the two-piece split nut, with the channel(s) on the locking ring aligned with the protrusion(s) on the split nut, thereby holding the split nut together.
In an embodiment of the invention the split nut includes at least four rectangular protrusions that are aligned parallel to the axis of the split nut, and the locking ring has similarly disposed channels.
In an aspect of the invention, an inwardly projecting locking tab is provided in each channel that engages the split nut protrusion when the split nut is fully inserted into the locking ring.
In another aspect of the invention the locking ring may engage the split nut from the threaded pipe side of the joint whereby only a minimal length of the flanged pipe need be free of obstruction.
In an embodiment of the invention, the split nut is provided with a plurality of circumferentially-oriented locking pins and corresponding locking apertures that engage to facilitate proper alignment of the split nut portions.